1. Technical Field
This disclosure generally relates to stacked semiconductor devices and more particularly to multi-stacked semiconductor dice with enhanced board-level reliability and integrated electrical functionalities over a common package foot-print.
2. Description of the Related Art
Multi-stack semiconductor structures include laminate Ball Grid Array (BGA) structures and Three Dimensional (3D) Integrated Circuits. Laminate BGA structures include semiconductor dice and at least one laminate substrate. In a laminate BGA structure, a first semiconductor die includes a bottom surface to be attached to a circuit board and an upper surface. The upper surface of the first semiconductor die is attached to one side of a laminate substrate through solder joints. An opposed side of the laminate substrate is attached to a bottom surface of a second semiconductor die through solder joints. Laminate BGA structures can be extended to more two levels by adding more laminate substrates and semiconductor dice. For example, a third semiconductor die may be stacked thereon with an additional laminate substrate connecting the second and third semiconductor dice together.
A problem with laminate BGA structures is that the laminates interposing adjacent semiconductor dice add to the overall height of the package. In some applications, it may be desirable to reduce the overall height of the package.
Three Dimensional (3D) Integrated Circuits (IC) have multiple integrated circuits stacked one on top of the other. In 3D IC structures one integrated circuit is connected to an adjacent integrated circuit by through-silicon vias that create vertical connections through the body of the die. These structures are complex to manufacture.
Multi-stack semiconductor structures are increasing in functionality and complexity. A consequence of the increased functionality is that the multi-stack semiconductor structures are increasing in size and have a larger foot-print on a circuit board. There are problems with merely increasing the foot-print size of the multi-stack semiconductor structure to provide additional functionality. For example, it may be desired to reduce the overall size of the circuit board, and in that case, it may not be desirable to increase the size of the foot-print of the multi-stack semiconductor structure.